Iraq is interested in getting the Russian S-400 air defenses. Earlier this week an Iraqi delegation traveled to Moscow to discuss buying it. The Russian defense industry has confirmed Iraqi interest and the Russian ambassador to Baghdad confirms Russia woul be happy to sell.

Heather Nauert: Iraq 'needs to make a choice'

So albeit nothing concrete has happened yet the US is already warning Iraq not to go through with the purchase (27min, 52s):

During a press briefing State Department’s Heather Nauert has explained the US has informed Baghdad getting Russian air defenses would go against America’s Countering America’s Adversaries Through Sanctions Act of 2017 which imposed sanctions on Iran, North Korea and Russia — which would mean Iraq would be facing US sanctions for doing business with Russia.

QUESTION: Okay. Let me ask you about Iraq. It’s getting – you’ve described the terrible things that Russia is doing in Syria, whether Russia’s activity in Iraq would be deny – benign. Iraq recently received Russian tanks, T-90 tanks, and it’s reportedly considering the purchase of the S-400 air defense system. What is your comment on that and would those transactions make Iraq susceptible to CAATSA sanctions?

MS NAUERT: Well, first of all, we are communicating with governments all around the world, such as Iraq and others, about the CAATSA law, and making those governments aware of how they could run afoul of the CAATSA law and the potential repercussions as a result. So we made it clear to all of those – all of – many of the countries that we work with – information about our new law. So let me – I just want to be clear about that.
Secondly, I don’t know if this deal that you speak of is a done deal or not, so I’m not going to get ahead of what that may be, but I can just tell you that we make it clear with our partners and allies.

QUESTION: So it sounds like, from what you’re saying, if this S-400 deal were to go ahead and be concluded, they could be in violation of CAATSA?

MS NAUERT: Look, that’s a hypothetical, but we have made it clear to countries around the world this is our law, this is what will cause your country, your government to run afoul of the law, and countries then need to make a choice.

Iraq has traditionally got its arms imports from Moscow and has recently concluded a $4.7 billion weapons deal with Russia that included purchases of T-90 tanks and BMP-3 vehicles. Before the unexpected rise of ISIS in 2014 Baghdad was in talks to purchase the Russian S-300 air defenses.

China and India, as well as traditional US clients Turkey, Saudi Arabia, Egypt and Qatar have already ordered the missiles or are interested in doing so.